1. Field of the Inventions
The invention relates to a tubular bone anchoring element (implant) for prosthetic constructions.
2. Description of the Related Art
It is previously known to anchor temporarily or permanently for example epitheses and hearing aids as well as tooth crown and tooth bridge constructions by means of oseo-integrated implants, often via extension units, so called abutments, perforating mucous membrane. The implants most often comprise compact threaded screws, which are screwed into the bone after a screw hole has been drilled. Either the implants are allowed to be oseo-integrated after covering by mucous membrane and are then connected with abutments after perforation of the mucous membrane, or the implants are connected directly to the abutments thereof or the prosthetic construction.
DT 2628485 A1 describes an arrangement for anchoring artificial teeth as a tubular structure. Both the side wall and the end wall of the tube are perforated so that the lumen of the tube is in direct connection with the bone tissue outside the tube (see FIG. 19), or the wall is porous to be able to let through liquid and tissue components from the bone as well as covering connective tissue. This involves a very great risk for contamination between the mouth cavity and the lumen of the tube if an infection arises around the implant. If there additionally arises some bone resorption around the implant, as is most often the case the consequences can be devastating for the implant when the infection and bone resorption extend to the lumen of the implant via hollows and porosities in the implant wall. This prior art implant has no threads neither on the inside surface nor on the outside surface of the sidewall but it is stated that there may be a helical ridge on the outside surface. The implant is substantially intended to be hacked or pressed down into a trephine-drilled groove. The lumen thereof moreover has a bone contact surface. The implant referred to cannot provide conditions of bone enlargement. Moreover it has preferably an outside diameter of only 4 mm.
A less immediate example of an implant is disclosed in WO 96 19 947. This implant certainly is tubular but only at the apical third part thereof, i.e. the third part most remote from the tooth crown. The upper part located adjacent the tooth crown is compact and is received by a blind hole for a screw attachment for the abutment of the tooth crown. This means that this implant has a small bone contact surface and requires removal of a considerable amount of bone at the insertion of the implant. The small extension of the apical cavity implies that the implant does not provide conditions for bone enlargement. It is not provided with threads neither on the outside surface nor on the inside surface of the sidewall. Also this implant preferably has an outside diameter of only 4 mm.
EP 0 083 558 describes a bone anchoring element comprising a tubular implant to be inserted into bone tissue for anchoring a prosthetic component located outside the bone said implant being open at one end which is intended to be inserted into the bone tissue while the implant at the other end, intended to be directed towards portions located outside the bone tissue is closed by a compact impermeable end wall portion having an attachment for the prosthetic component on the outside thereof the lumen extending from the open end through the total implant to the end wall portion so that the lumen after insertion of the implant in the bone tissue includes at least the total portion of the implant, which is intended to be anchored in the bone tissue.